Searching for good learning sources for GenAI in pure Python

Hey I'm new here.

Currently I want to finish my Python learning soon and then start my deep dive into the GenAI field.

I already searched for good learning sources (thats why I ended up here 😅) but noticed that a lot of the GenAI tutorials immediately start with using frameworks.

Mainly LangChain and LlamaIndex seem to be the choices for tutorials with RAG, Agents, etc.

As easy as it may be to get started with 2 lines of code with a framework, I actually like to learn what is going on behind the scenes and how the different systems actual work.

Furthermore Dave and other experts mention that these Frameworks are rarely used in production.

My thinking is I want to learn it right and in detail from the get go instead of having everythin important abstracted away.

So, do you have good sources for learning material that focuses on pure Python and explains the basic and advanced concepts?